Enhanced phosphorus diffusion during the glow discharge deposition of n-type amorphous silicon hydrogen alloy

Phosphorus outdiffusion during glow discharge deposition of amorphous silicon hydrogen alloy (a-Si:H) is investigated. From the measurement of phosphorus profile using secondary ion mass spectroscopy on a double layer structure (n+/i/quartz and i/n+/quartz), it is found that the thermally assisted phosphorus diffusion is negligibly small at 300 °C. However, the phosphorus diffusion is enhanced significantly after passivation with hydrogen plasma at the same temperature. It is proposed that the release of phosphorus by atomic hydrogen to form PHx radicals is the rate limiting step for enhanced diffusion.